So, apparently the person at my local mediacom office gave me a cablecard that's paired with a set-top box. So on my account, I'm still being charged for the box, and not just a cablecard ($15 vs $2). I need to swap out the cablecard currently in my tivo for a new one (which i have) that's a standalone card.

My question is, is there anything special I have to do?

I'm assuming I need to power off TiVo, and do the swap, and go through guided setup again. Or at least the cablecard configuration.

You don't have to power down the Tivo or repeat guided setup (which would be the easy part if required). Just pop the old card out, put the new one in, call the cable co number that activates/pairs cable cards, follow their instructions and provide the info they need to activate the card.